(1) Beating degree: Beating degree only represents the drainage performance of the pulp. With 2 g of absolute dry pulp, dilute to 1000 ml, and measure the amount of water discharged from the Shore's free-flow meter through a 80-mesh screen at 20 °C. Beating degree is an indicator of the nature of the paper stock. According to the degree of beating of the paper stock, it is possible to grasp the water filter speed of the paper stock in the future on the copper machine of the paper machine. It may also be generalized to predict the mechanical strength, tightness, and finish of the paper produced in the future. Sex and so on, so grasping the degree of beating of paper stock is an important technical control method in production. An index of purely beating does not fully represent the properties of the material. For example, we can use a highly severed fiber (free beating) to achieve 45° SR. In addition, high fibrillation (viscous beating) can also be used. , But not how to shorten the way to achieve the same 45 ° SR beating degree. In both cases, although the final degree of beating is the same, the nature of the paper stock is quite different. Therefore, the sole beating degree in production is the only control indicator in production technology. It has disadvantages, and still has to be compared with Other indicators such as the average length of fibers. Considered together, reasonable beating can be achieved.
There are many kinds of instruments for determining the degree of beating of paper materials. The papermaking machines in China generally use the Shore's beating instrument.
(2) Canadian Standard Freeness (csf): There are various methods for the determination of pulp drainage performance, among which the freeness and freeness have been widely used. In North America countries and Japan, Canadian standard freeness is mostly used, while in Europe and China, the degree of freeness of Shore's beating is commonly used. The difference in freeness and beating degree is just the difference in the method of determination. The greater the degree of beating, the smaller the freeness of the paper stock, and vice versa. In general, the faster the free paper, the faster the speed of filtration. The Canadian standard freeness measurement instrument is similar to the Shore Beater, but the absolute dry fiber sampling is 3 grams when measured. Freeness and freeness can be converted to each other.
(3) Water retention value: In the standard state, the free water in the paper stock is thrown by a high-speed centrifuge, and the amount of water retained in the paper stock is quantitatively determined, and the water retention value of the paper stock can be obtained and thus generated. Fiber plasticity. This method uses centrifugation to store only the swell water between the fibers, but only a small amount of water between the surface of the fiber and the fibers. Therefore, the water retention index can indicate the degree of swelling of the fiber and reflect the degree of fibrosis. It shows the size of the binding force between fibers.
Beating degree can only determine the drainage performance of the paper, but the increase in the degree of freeness does not mean that the paper strength will increase linearly. The increase in water retention value in the pulping process tends to be consistent with the increase in strength. The strength of the paper depends mainly on the bonding strength between the fibers and the length of the fibers, so measuring the water retention value and measuring the average length of the fibers will give a good indication of the strength of the paper. At present, it is generally considered that the determination of these two indicators can explain the problem better than merely using the freeness index. However, because the equipment is expensive and the measurement procedures are more cumbersome, the application is not universal enough. At present, domestic paper mill production has not yet been formally adopted.
(4) Wet weight: Wet weight is a term commonly used in the control of the beating process, which indirectly shows the average length of the fiber. Wet weight is measured by the frame method. A special frame is used to make the diluted paper stock flow through the frame while measuring the degree of freeness. The weight of the fiber caught on the frame is the wet weight. The longer the average fiber length in the paper stock, the heavier the fiber that is hung on the frame, ie, the greater the wet weight.
(5) Degree of hydration: Some factories also use the degree of hydration as an indicator. First of all, in the paper industry, the term “fiber hydration†is not strict enough because it is easy to misunderstand that fiber and water play a role in chemistry. In fact, water forms a water bridge with hydroxyl groups on the fiber and dehydrates to form hydrogen when dried. The key is not a chemical effect. The degree of hydration is a measure of the amount of water absorbed by the fibers during the beating process. One of the methods for determining the degree of hydration is the boiling method, which is heating the boiled paper material for 1 hour, removing the bound water of the fiber by heating method, and then determining the degree of beating according to an ordinary method; using unheated paper material and heating boiled paper stock paper The difference in beating degree measured by the material respectively represents the degree of hydration of the paper material fibers. The other is the alcohol method, in which the paper stock is placed in alcohol, and the combined water of the fibers is replaced with alcohol, and then the degree of beating is determined by an ordinary method. The difference between the paper material and the alcohol measured in water indicates the paper. The degree of hydration of the material. Both of the above methods for measuring the degree of hydration of a fiber have some drawbacks and are prone to errors.
Canadian Standard Freeness and Shore Freeness Conversion Table Canadian Standard Freeness (ml) Shore Freeness (°SR) Canadian Standard Freeness (ml) Shore Freeness (°SR) 25 90.0 425 30.0 50 80.0 450 28.5 75 73.2 475 26.7 100 68.0 500 25.3 125 63.2 525 23.7 150 59.0 550 22.5 175 54.8 575 21.0 200 51.5 600 20.0 225 48.3 625 18.6 250 45.4 650 17.5 275 43.0 675 16.5 300 40.3 700 15.5 325 38.0 725 14.5 350 36.0 750 13.5 375 34.0 775 12.5 400 32.0 800 11.5
There are many kinds of instruments for determining the degree of beating of paper materials. The papermaking machines in China generally use the Shore's beating instrument.
(2) Canadian Standard Freeness (csf): There are various methods for the determination of pulp drainage performance, among which the freeness and freeness have been widely used. In North America countries and Japan, Canadian standard freeness is mostly used, while in Europe and China, the degree of freeness of Shore's beating is commonly used. The difference in freeness and beating degree is just the difference in the method of determination. The greater the degree of beating, the smaller the freeness of the paper stock, and vice versa. In general, the faster the free paper, the faster the speed of filtration. The Canadian standard freeness measurement instrument is similar to the Shore Beater, but the absolute dry fiber sampling is 3 grams when measured. Freeness and freeness can be converted to each other.
(3) Water retention value: In the standard state, the free water in the paper stock is thrown by a high-speed centrifuge, and the amount of water retained in the paper stock is quantitatively determined, and the water retention value of the paper stock can be obtained and thus generated. Fiber plasticity. This method uses centrifugation to store only the swell water between the fibers, but only a small amount of water between the surface of the fiber and the fibers. Therefore, the water retention index can indicate the degree of swelling of the fiber and reflect the degree of fibrosis. It shows the size of the binding force between fibers.
Beating degree can only determine the drainage performance of the paper, but the increase in the degree of freeness does not mean that the paper strength will increase linearly. The increase in water retention value in the pulping process tends to be consistent with the increase in strength. The strength of the paper depends mainly on the bonding strength between the fibers and the length of the fibers, so measuring the water retention value and measuring the average length of the fibers will give a good indication of the strength of the paper. At present, it is generally considered that the determination of these two indicators can explain the problem better than merely using the freeness index. However, because the equipment is expensive and the measurement procedures are more cumbersome, the application is not universal enough. At present, domestic paper mill production has not yet been formally adopted.
(4) Wet weight: Wet weight is a term commonly used in the control of the beating process, which indirectly shows the average length of the fiber. Wet weight is measured by the frame method. A special frame is used to make the diluted paper stock flow through the frame while measuring the degree of freeness. The weight of the fiber caught on the frame is the wet weight. The longer the average fiber length in the paper stock, the heavier the fiber that is hung on the frame, ie, the greater the wet weight.
(5) Degree of hydration: Some factories also use the degree of hydration as an indicator. First of all, in the paper industry, the term “fiber hydration†is not strict enough because it is easy to misunderstand that fiber and water play a role in chemistry. In fact, water forms a water bridge with hydroxyl groups on the fiber and dehydrates to form hydrogen when dried. The key is not a chemical effect. The degree of hydration is a measure of the amount of water absorbed by the fibers during the beating process. One of the methods for determining the degree of hydration is the boiling method, which is heating the boiled paper material for 1 hour, removing the bound water of the fiber by heating method, and then determining the degree of beating according to an ordinary method; using unheated paper material and heating boiled paper stock paper The difference in beating degree measured by the material respectively represents the degree of hydration of the paper material fibers. The other is the alcohol method, in which the paper stock is placed in alcohol, and the combined water of the fibers is replaced with alcohol, and then the degree of beating is determined by an ordinary method. The difference between the paper material and the alcohol measured in water indicates the paper. The degree of hydration of the material. Both of the above methods for measuring the degree of hydration of a fiber have some drawbacks and are prone to errors.
Canadian Standard Freeness and Shore Freeness Conversion Table Canadian Standard Freeness (ml) Shore Freeness (°SR) Canadian Standard Freeness (ml) Shore Freeness (°SR) 25 90.0 425 30.0 50 80.0 450 28.5 75 73.2 475 26.7 100 68.0 500 25.3 125 63.2 525 23.7 150 59.0 550 22.5 175 54.8 575 21.0 200 51.5 600 20.0 225 48.3 625 18.6 250 45.4 650 17.5 275 43.0 675 16.5 300 40.3 700 15.5 325 38.0 725 14.5 350 36.0 750 13.5 375 34.0 775 12.5 400 32.0 800 11.5
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